Two models of the biological consequences of herpesvirus infection - cytocytal infection and biological and/or oncogenic transformation - are available. Equine herpes-virus type 1 (EHV-1) causes abortions while equine herpesvirus type 2 (ECMV) is a cyto-megalovirus that causes systemic diseases in horses. The two viruses differ in several biological and physical properties: (1) EHV-1 has a highly lytic infection whereas ECMV has a very slowly developing cytopathology; (2) EHV-1 and ECMV have genomes of 92 md and 126 md, respectively; and (3) the EHV-1 genome has one unique short region (22 md) flanked by repeat regions that allow the DNA to exist in two isomeric forms; the ECMV genome has two unique short regions (6 md and 12 md each) that are flanked by repeat region. These viruses do share genetic homology and are capable of establishing persistent infections and oncogenically transformed cells. All EHV-1 and ECMV transformed and tumor cells express viral polypeptides and contain viral sequences. The EHV-1 sequences present in transformed cells are integrated and are amplified by tandem duplications during tumorigenesis. ECMV transformed and tumor cells retain specific viral sequences. Virtually nothing is known about the viral transcriptional process in lytically infected cells and nothing is known about the viral transcripts present within oncogenically transformed or tumor cells. The goals of this proposal are: (1) to detect and identify viral transcripts in EHV-1 or ECMV lytically infected cells by formaldehyde agarose gel electrophoresis; (2) to determine whether the transcriptional process in cycloheximide- or Fudr-treated and drug free lytically infected cells can be divided into immediate early, early and late phases; (3) to map the locations of the viral transcripts using Southern, dot and Northern blotting techniques; (4) to determine by S1 endonuclease digestion whether post-transcriptional processing of viral transcripts such as splicing, occurs; and (5) to compare the transcriptional map of EHV-1 to ECMV in order to identify common or unique transcriptional strategies. These same techniques will be used to examine the nature of the viral transcripts present in EHV-1 and ECMV oncogenically transformed or tumor cells. The data will be evaluated so as to correlate the transcriptional patterns to the type of infection (transformation, oncogenic) and copies of integrated viral sequences.